Provided there are no more cock-ups - the first public Eurostar train between London and Paris will emerge from the south portal of the Channel Tunnel and into the light of northern France and, 15,000 years after the land bridge was inundated by the Straits of Dover, Britain will effectively have ceased to be an island once again.

This astonishing development has not caught the imagination of the British people quite as much as it might have done. This may be to do with the fact that the Tunnel saga has been going on at least since the Treaty of Amiens in 1802, and a certain amount of weary scepticism is understandable. It may be connected with the delays and overruns and locomotive failures and bad publicity that we have heard over the past few months.

But it is impossible to avoid noting that the Tunnel opens at a time when British attitudes seem more, well, insular than ever. Only yesterday morning - to take one small but telling example - the Radio Four headlines announced that the Briton Damon Hill had failed to become world motor racing champion. Nine minutes later it was thought worth mentioning that the German Michael Schumacher had succeeded in taking the title.

The governing party's attitude to European co-operation is well known. The country's biggest-selling paper regularly insults Krauts and Frogs. And yet, from today, it will take 21 minutes to get from one side of the Channel to the other. If the Government had not so ineptly failed to will the means of actually getting to the Tunnel, it would now be possible to travel faster from London to Paris than to Manchester, Liverpool or Leeds.

It will, even so, be quicker and easier than ever before to get not merely to Paris for lunch and shopping, but to a whole range of places in north-west Europe. And it is now possible, travelling solely by train, to make all kinds of other new and bizarre journeys. We know: we have proved it.

You can now go from Aberdeen, Aberdovey or Abergavenny to Zweisimmen (Switzerland), Zwolle (Netherlands) or Zywiec (Slovakia). It is possible, merely changing trains, to get from Thurso to Shanghai, Kowloon or Ho Chi Minh City, though probably not on Guardian expenses. In Europe alone, you can now go to Bo, Brig, Bled, Blaj, Dno, Drama, Elk, Gap, Gent, Most or Vic. With the benefit of a Eurostar freebie on one of last week's test runs, I went to Hel.

This was partly because the Polish port of Hel, at the tip of a peninsula north of Gdansk, looked like an interestingly obscure destination on the Thomas Cook rail map, with a name that might lend itself to the odd, strictly rationed, cheap joke. (There is a town and station in Norway spelled Hell but the only direct railway route would be via St Petersburg, and even then you run out of rails for 100 miles in Lapland.) And going to Poland was very educational, not just about another country, but about this one.

On the way, photographer Sean Smith and I became, subject to ratification and competing claims, the first people ever to travel by railway all the way from London to Berlin: one small step for a man, one pretty small step for mankind - but, I would venture, a fairly evocative one. Anyway, we were sure as hell the first to get to Hel and back.

This involved travelling on Eurostar train number 9010 (solemnly announced, as though there were another 9,009) from Platform 22 at Waterloo , ambling through south-east London, speeding up a little through Kent with officials anxiously explaining that the trains were very deceptive and we were going faster than it seemed, doing the ton under the Channel and then racing through the dreary flatlands between Calais and Paris at three miles a minute without noticing it. We arrived eight minutes late (red light near Westenhanger).

The second-class seats were cramped, the catering indifferent. But compared to planes and ferries, it was sensational: the most brilliant way of going abroad ever invented.

While the other freebiers strolled off for lunch, we made a one-stop hop on the Metro to Gare de l'Est, caught the 13.05 to Frankfurt with two minutes to spare, changed trains at Mannheim on to a perfectly routine German inter-city service that can only have been a fraction less comfortable than the Orient Express - and arrived at Berlin Zoologischer Garten station in 15 hours 46 minutes two seconds. We were 58 seconds early, this being Germany. It would be about four hours quicker to go via Brussels, an option available today but not last week.

It is not difficult to go on to Gdynia, the junction next to Gdansk, provided you can cope with the only train of the day being at 06.32. Going east, the carriages get older, the coffee, the service and the toilet paper rougher, the soap dispensers emptier, the chimneys outside smellier and the paint greyer.

But past the Polish border at Szczecin something extraordinary happens. You arrive on a railway system bearing a most remarkable resemblance to British Rail circa 1964. The post-communist masters of the nationalised Polish railway system are embarking on a system of Dr Beeching-style cutbacks. Already, some rural lines have closed many more will follow.

The old lines are fading away. Just west of Gdynia a bridge was down and the train from Berlin had to be diverted down a line, officially now closed, between Slawno and Korzybie. We crept slowly past hummocky grey-green fields, forlorn cabbage patches, mushroomy woods, geese padding through marshy gullies and not a soul in sight. It was a damp, gunmetal, communist sort of day. But the journey still seemed enchanted, as though we were travelling to Adelstrop East.

The remaining bits of the Polish system are not merely splendidly complex but, if not exactly efficient, then punctual. The trains are a riot of competing liveries: crimson, bottle-green, lime-green, peaches-and-cream, blueberries-and-cream. Most of the carriages on the morning train to Hel were painted a sort of dark-mud.

The only daylight service at this time of year is another bummer: 06.48 from Gdynia. But it was a very pleasant, dozy sort of train with those old, comfy but faded six-seat second-class compartments so redolent, to anyone of a certain age, of British train travel in the 1950s and 1960s.

It took two hours to cover 50 miles, north to the junction at Reda and then east across the narrow peninsula. The train was almost empty except for a brief and noisy interlude when the kids of Zelistrzewo got on for their morning journey to school. All that was missing were those parallel mirrors in which you could see yourself for ever and a jolly-fisherman advert for Skegness.

Hel turned out to be bracing too. It is strategically important, and was both the last town in Poland to be captured by the Germans, and the last to be liberated. It is also rather a nice place, with a piney smell, cool in summer and mild in winter. There are a few blocks of flats of the sort built only by communist regimes and British borough councils, but none of the Stalinist towers that dominate the cities. There is no hotel but city-dwellers from Gdansk and Gdynia go there in summer on day trips by ferry and train the sea on their side of the bay is horrendously polluted.

The peninsula is merely a sand-spit and very fragile it was a cluster of islands until a few centuries ago and could easily be split by the sea again one stormy night. The authorities thus discourage travel by private cars. The road to Hel really is paved with good intentions.

On a late-autumn morning there is more life round the little half-timbered station than anywhere else. A few housewives arrived for the shoppers' train back to the city. Great diesel engines shunted wagons round the sidings. A tubby man in a pair of grubby overalls then emerged from a back room to swing a hammer at the couplings in a desultory sort of way. Thus it was at thousands of little British stations many years ago.

The line to Hel will probably not be closed, unlike the nearby branches to Leba and Darlowe and Slawoborze. Instead, it will probably soon be down to a couple of little trains a day, the Polish equivalent of Sprinters. Doubtless someone will decide it is more economic to send the freight down the narrow road, and the weeds will grow between the rusting rails in the goods sidings. The driver doing the shunting, the man with the hammer, and the woman selling tickets behind a net curtain, will all be made redundant, and the government will have to pay them to do nothing all day, instead of not all that much. Cui bono?

The main trunk routes of the Polish system are not going to be closed, because the roads and internal aviation system are still too bad to make them competitive. Poles habitually travel between their cities by trains that retain a certain grandeur. The post-totalitarian ticket-collectors maintain a dictatorial swagger and wear militaristic caps with bits of scrambled egg on them, an effect slightly dissipated as you look down because, unlike real uniformed authority-figures, they never remember to clean their trouser-bottoms and boots.

And there is now an attempt at marketing. On the inter-city trains, a steward comes round handing out free coffee and chocolate bars, a cheap gesture that ensures that every child in the country begs to be allowed to travel on them.

Hel is one of Europe's railway outposts, like Britain. But Poland itself is at the heart of the continent, so much at the mercy of history and geography that it disappeared for more than a century, carved up among its greedy neighbours. By night Warszawa Centralna station is the haunt of the city's new down-and-outs. By day it is possible to go from there to anywhere in Mitteleuropa and on east to Minsk, Moscow, Ulan Bator, Beijing and, if the connecting service is running, down into Vietnam.

One gets a sense that the future of the world is here somewhere. It has snowed history in these parts. No one needs to tell the Poles that Europe matters.

For Britain it is different. Blinded by the failures of the Brussels institutions - rigid, remote, bureaucratic, anti-democratic and, in their well-heeled way, rather sleazy - we have put ourselves into a position where we have insufficient influence to get them reformed, and have misunderstood their relevance, and that of Europe itself.

If British cabinet ministers ever stood in the cold dawn at a German railway station, desperate for a cup of coffee while carrying a pocketful of assorted French, Belgian and British change and maybe a million-zloty note (worth pounds 25), they would be not quite so dismissive about the idea of a European currency.

No youngster who has travelled round Europe by train would talk about the Continent with the pathetic negativity of a Conservative MP. Out there, a tunnel's length away, is a diverse, fascinating, changing continent that we persist in regarding as unspeakably boring. It may be the undoing of us as a nation, unless the end of physical insularity also marks the end of our psychological insularity.

In the meantime, anyone who wants to go to the ticket office at Aberdeen, Aberaeron or wherever to ask if it is possible to get a Supersaver to Hel can do so, at their own risk.